The Tyndall effect is a phenomenon that occurs when light is scattered by particles in a colloidal solution. Colloidal particles are typically larger in size compared to the molecules in a solution and are dispersed throughout the medium.

Option 1 correctly states that the Tyndall effect is a result of the scattering of light by colloidal particles. When light passes through a colloidal solution, it interacts with the particles and gets scattered in different directions. The scattered light can be observed as a visible beam or path of light within the solution.

Option 2, which suggests that the Tyndall effect is caused by the refraction of light by colloidal particles, is incorrect. Refraction occurs when light passes through a different medium and changes direction due to a change in speed. While refraction can occur at the interface of different mediums, it does not explain the Tyndall effect.

Option 3 states that the Tyndall effect is a result of the dispersion of light by dust particles. This is also incorrect as the Tyndall effect specifically refers to the scattering of light by colloidal particles, not dust particles.

Option 4, suggesting that the Tyndall effect is caused by the refraction of light by dust particles, is also incorrect. Again,